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APPENDIX F Precautions on Handling
- Set a break point within the above sequence of instructions.
- Execute step within the above sequence of instructions.
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Notes on using PS register
PS register is processed by some instructions in advance so that exception operations as stated below may
cause breaks during interruption processing routine when using debugger and may cause updates to the
display contents of PS flags.
In either case, this device is designed to carry out reprocessing properly after returning from such EIT
events. The operations before and after the events are performed as prescribed in the specification.
1. If the instruction immediately before DIV0U/DIV0S instruction (a) receives a user interrupt/NMI, (b)
executes stepping or (c) breaks by data event or emulator menu, the following operations may be
performed.
(1) D0 and D1 flags are updated in advance.
(2) EIT handling routine (user interrupt/NMI, or emulator) is executed.
(3) After returning from the EIT, DIV0U/DIV0S instruction is executed and the D0 and D1 flags are
updated to the same values as in (1).
2. The following operations are performed if each instruction from ORCCR, STILM, MOV Ri and PS is
executed to allow an interruption while user interrupt/NMI trigger exists.
(1) PS register is updated in advance.
(2) EIT handling routine (user interrupt/NMI) is executed.
(3) After returning from the EIT, the above instructions are executed and the PS register is updated to
the same value as in (1).
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Watchdog timer function
The watchdog timer equipped in this model operates to monitor programs to ensure that they execute reset
defer function within a certain period of time and to reset the CPU if the reset defer function is not executed
due to the program runaway. Therefore, once the watchdog timer function is enabled, it keeps its operation
until it is reset.
By way of exception, the watchdog timer automatically defers a reset under the conditions where the CPU
program executions are stopped. For more detail about such conditions, refer to the description section of
the watchdog timer function.
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